<html>
<head>
    <title>日期计算机</title>
</head>
<body>
    <header>日期计算器</header>
    <article>
        <form action="calculate.php" method="post">
            <table>
                <tr>
                    <td>年</td>
                    <td><input type="text" name="year" id="year"></td>
                </tr>
                <tr>
                    <td>月</td>
                    <td><input type="text" name="month" id="month"></td>
                </tr>
                <tr>
                    <td>日</td>
                    <td><input type="text" name="day" id="day"></td>
                </tr>
                <tr>
                    <td colspan="2">
                        <input type="submit" name="calculate" value="计算">
                    </td>
                </tr>
            </table>
        </form>
    </article>
</body>
</html>